Starting and idling system for gaseous fuel feeds



R. F. l-:NsGN

STARTING AND IDLING SYSTEM FOR GASEOUS FUEL FEEDS Filed June a, 195s June 11, 1957 STARTING AND IDLING SYSTEM FOR GASEOUS FUEL FEEDS Roy F. Ensign, San Marino, Calif., assignor to Ensign Carburetor Company, Huntington Park, Calif., a corporation of California Application .lune 8, 1953, Serial No. 360,102

12 Claims. (Cl` 48-184) This invention has to do with provisions for starting, and for idling operation, of internal combustion engines fed with gaseous fuel; and the general purpose of the invention is to provide a simple form of starting system and a combined starting and idling system which may be used in connection with any standard gas carbureter which is fed with gaseous fuel from any kind of pressure regulator. As will become apparent from the following description, the pressure regulator may either be a simple one adapted merely to deliver gas fuel at a uniform pressure, preferably slightly sub-atmospheric; or it may be one in which the regulating action is modified to increase the delivery pressure for idling and/or starting operations, or is modified for fuel economy. See for instance Ensign Patents 2,073,299 and 2,248,222. Or it may be one which normally delivers at substantially atmospheric pressure. See for instance my application filed December 9, 1952, Ser. No. 324,986. 'Ihe action of the idling and starting system of the present invention is the same in any such case; consequently, for simplicity, the following description will proceed basically on the assumption that the pressure regulator delivers the fuel gas to the carbureter at uniform pressure, slightly subatmospheric so that the regulator will automatically close down when pressure at the delivery becomes atmospheric.

The invention will be best understood from the following descriptions of the typical and illustrative embodiments shown in the accompanying drawings, wherein:

Fig. l is a schematic showing, with parts in section, of an illustrative embodiment;

Fig. 2 is a sectional view showing modification of portions of Fig. l; and

Fig. 3 is a sectional view showing further modifications.

ln Fig. l a regulator, shown schematically at 10, delivers gaseous fuel (e. g. butane) under regulated pressure through a delivery passage 12 to a relatively restricted gas nozzle 14 located in the throat of carbureter venturi 16. The carbureter can be of any standard type having a venturi or equivalent formation through which air is drawn from air intake 18, and having a throttle 20 in the mixture passage 22 on the engine side of the venturi. The mixture passage on the engine side of the throttle can be considered a part of the engine intake manifold 23, as manifold pressures are always present there. Regulator may be of any suitable type and, as indicated above, it may have its action modified to vary its delivery pressure; but for the purpose of this description it will be assumed to deliver either at `an unvaried uniform atmospheric or slightly sub-atmospheric pressure, or basically at such a uniform pressure slightly modified under varying operating conditions of the engine. The action of the present invention is the same in either case; and it is one of the advantages of the present invention that it provides a simple starting, and combined starting and idling system, which can be used with a simple regulator which merely delivers at an unmodified constant sub-atmospheric pressure.

The delivery passage 12, as here shown, includes a States Patent *n portion 12a. formed asa passage in the carbureter casting and which lies immediately adjacent the relatively restricted fuel delivery nozzle 14. It is important, particularly if the regulator delivers at sub-atmospheric pressure, that there be an effective ow impediment, in practice a restriction of some kind relative to they size of delivery passage 12, 12a, close to the delivery point in the Venturi, and that the idling and starting passages which are now to be described connect with the relatively unrestricted delivery passage on the regulator side of the restriction 'as close to the restriction and the delivery point as` may be practicable. The restriction need not be the delivery nozzle itself; it can be for example an adjustable valve in the delivery passage close to the venturi throat.

In the particular, but merely illustrative, arrangement of passages shown in Fig. l, a port 24 communicateswith the mixture passage (the intake manifold) on the engine side of throttle 20 and forms part of a relatively unrestricted passage 26 which leads to two restricted passages 28 and 30. Passage 28 is adjustably restricted by needle valve 32 which constitutes the idling adjustment. Passage 30 is preferably fixedly,` although changeably, re'- stricted by being formed as a calibrated orifice of chosen size. The restricted idling passage 23 is connected to delivery passage 12 by a suitable larger passage 34. Restricted passage 30 is connected to 12 via a passage 36 which is controlled by a valve 38 which may seat on a seat 40 to close the passage. As shown in Fig. l, valve 38 is a ball located under seat 4i? in passage 36. When manifold suction at 30 is, generally speaking, not greater than that caused by starting turnover of the engine with the throttle in a closed position, ball 38 will not be drawn up onto seat 40, but willremain in such a position as shown where it rests on some suitable support such as pin 42 which prevents the ball from dropping down into. main passage 12a. When the suction at 30, in general, exceeds the starting suction (as when the engine starts operation) then ball 3,8 is drawn up ontoseat 4l), closing passage 30. In any normal range of operation, including idling, the suction at 30 will exceed the starting suction; and consequently ball 38 can be arranged to be in lower open position during starting turn-over, and in upper closed. position throughout all ranges of normal engine operation.

For purposes of description, but not of restriction, of the invention, let it be assumed that regulator 10 delivers to passage 12, 12a at a pressure equal to one-quarter inch of Water below atmospheric. Let it also be assumed that the manifold depression on starting turn-over may be as low as, say, an inch of mercury with slow turn-over of a cold engine, or as high as say ve inches of mercury with fast turn-over of a hot engine, with throttle 2t) in a closed (idling) position. Then the size of orifice 30 is chosen so that with the throttle closed down to idling, on any starting turnover fast enough to start the engine and which may produce only the minimum manifold depression, enough gas is drawn through 30 and the idling-adjusted passage at 28 to form an overly rich mixture with air drawn past the closed throttle and air drawn in reverse ilow through nozzle 14 and into passages 34 and 36. At any starting turn-over speed with throttle closed, the air velocityV through the venturi is ordinarily not enough to produce suicient pressure drop to draw gas from 12 at the sub-atmospheric pressure at which the regulator delivers. Consequently with the starting depression at 26 applied through 30 and 28 to 12, air is drawn reversely (toward the right in Fig. 1) through 14. The fact that that nozzle 14 or equivalent is restricted relative to 12, then produces a pressure drop in 12 suicient to vcause the regulator to open and feed gas at its set Adelivery pressure.

Passage sizes suitable for the foregoing operation in a carbureter having an ai; and mixture passage say one and one-quarter inches in diameter, may be as follows. Passage 12, 12a, 0.5 inch diameter; nozzle 14 0.3 inch diameter; orifice 30 0,08 inch diameter. The adjusted effective size of passage 28, adjusted to its proper size to act as an idling by-pass between 12 and the intake manifold, is only a fraction of the size of orijice 30, asthe manifold depression at idling is much greater than on starting turn-over. f

I mean by overly rich mixture at least one which vis on the rich side of the leanest combustible mixture; so

as to be sure that the system will produce a combustible f mixture on starting turn-over. And preferably in practice I mean a mixturethat is on the rich side of perfect combustibilty or on the rich side of the whole combustible mixture range; so -as to be sure that the system produces a combustible mixture as the throttle is opened and the mixture thinned.

With the sizes of those parts determined by the foregoing considerations, the size and weight of ball 38 and its clearance in passage 36 are so chosen as to make the ball stay in its lower, open position during starting turnover and then to move up to closed position as soon as the engine starts operation. When it is said that the ball valve stays open during starting turn-over, that does not necessarily mean that it remains open during fast starting turn-over of a warm engine which can start readily or on a. relatively lean mixture. It means that the valve stays open for at least the starting suction produced in a cold engine. In practice, however, it is best to choose the several factors so that the valve stays open at the highest starting suction likely to be produced in a warm engine with a closed throttle. As an illustration, for cooperation with such dimensions as previously given, ball 38 may be a steel ball 0.35 inch in diameter, and passage 36, 0.48 inch in diameter. Passage 30 will then remain open during all likely starting speeds and close` immediately when the engine starts.

The operation of starting the engine requires no choking action of any kind on the carbureter air intake; that is one of the features of the invention. With the engine being turned over by the starting motor it is only necessary to allow the throttle to remain closed for a few turnover revolutions and then to gradually open the throttle as the motor continues to tum the engine over. During the closed throttle period the engine manifold becomes lled with an overly rich mixture. At wide open throttle during starting turn-over the mixture is incombustibly lean. At some intermediate throttle position the mixture drawn into the intake manifold is combustible and the engine will start. The small amount of air that has been drawn into 14, 12a, etc. during turn-over with closed throttle is quickly flushed out by gas from the regulator drawn by venturi depression through 14 as the throttle is opened. That is the reason why it is important to have the starting passage communicate with the main fuel passage at a point as close as practicable to the venturi. As soon as the engine has started valve 38 closes. The engine then operates normally; on fuel drawn through nozzle 14 in all power ranges; and on fuel drawn through by-pass passage 2S in idling operation.

It will be noted that the idling by-pass passage 2S and the valve controlled starting passage 30 connect the intake manifold to the gas delivery via two passages in parallel relationship. 'The fact that both passages communicate with the manifold through a single passage 24, 26 is immaterial. What is material is that the restricted idling passage 28 and the restricted, calibrated, valve controlled starting passage 30 form communications between gas feed and manifold in parallel relation. The two passages together forrn a passage means of a predetermined total effective size which is, altogether, large enough to provide fuel forstarting; and the valvular means acts, under the influence of the stated degree Vof manifold de pression, to reduce the eEective size to an effective size less than total, to provide fuel for idling.

Operation of the throttle for starting can be accomlished automatically; one suitable apparatus for the purpose being shown in Fig. l. A diaphragm 50 and casing 52 encolse a diaphragm chamber 54 that is connected by passage 56 with the intake manifold. In passage 56 there is a restriction 58 of chosen size and acut-off valve 60. The usual throttle closing spring is indicated' schematically at 62. An actuating rod 64 connects diaphragm 50 with throttle arm 66. The rod passes freely through a pin 68 mounted rotatably n the arm end, and the rod has a collar 70 on its end. Movement of diaphragm 50 to the left will pull on throttle arm 66 to open the throttle, but the throttle can be opened independently of the diaphragm because pin 68 can slide to the left on rod 64.

To start the engine valve 60 is opened and the engine turned over by its starting motor. Initially the throttle is in its closed position, due to spring 62. The manifold suction is transmitted restrictedly to diaphragm chamber 54 through restricted orifice S8. The diaphragm Y then moves slowly toward the left, opening the throttle at a rate determined by the size of orifice 58; the rate of movement being such as to allow the manifold first to become flooded with an overly rich mixture that is thinned out as the throttle opens; As explained above, at some point in the throttle opening and mixture thinning, a combustible mixture occurs and the engine starts. On starting, the increased manifold suction will tend to open the throttle wider and thus put the engine into normal operating condition. The throttle opening stroke of diaphragm 50 may be limited, as by the limiting seat 53, to open the throttle approximately only as Wide as is necessary -to idle the engine when cold. Then, after the engine has warmed up, or immediately it has started if it is already warm, valve 60 is closed. Any small leak, such as 72, into diaphragm chamber 54 will then allow the diaphragm and rod 64 to move to the right to allow the throttle to close to normal idling, Or valve 60 can be a three-way valve admitting atmosphere to diaphragm chamber S4 when the valve is turned to close the communication of passage 56 with the manifold.

Fig. 2 shows certain modifications that further illustrate the invention. In that figure parts which are in substance the same' as in Fig. l are given the same numerals. The modifications are in the automatic passageclosing valve and in the lrelation of the passage connection to the main fuel nozzle. l

As shown in Fig. 2 the automatic valve is in the nature of a at valve disk 8G which seats on a seat 82 to close, and is opened lby a spring 84 to connect passage 26 with a passage 86 that connects idling passage 28 with gas delivery 12a. The effective area of valve 80, the strength of spring 84 and the distance by which the open valve stands yoff its seat are the factors which control the effective suction, in 26, at which the valve closes; and those factors are designed to make the valve close as before explained. And the distance at which the valve stands off its seat when open, controlled by the limiting stops 85 can be madel to effectively form the calibrated orifice corresponding to 30 in Fig. l. Or the oritice 30 may be inserted in passage 26 as shown. Passages 24, 26 and 86 are relatively unrestricted as compared with the adjustable restricted idling passage 28 and the restricted passage 30 or that past open valve 80.

The action of the parts is the same as in Fig. 1, although the connection of the two restricted orices to the main gas lineis via the single passage 86', passages 28 and 30 are still in parallel relation.

As has been indicated at the inception of this description, the described starting provisions may be utilized either alone without the idling provisions, or with the latter to form a combined starting andidling system. Use of the `starting system alone involves -merely the elimination of the idling passage 28 as a connection paralleling the passage 30 of Fig. 1 or its equivalent in Fig. y2. If the idling passage is so eliminated then it may be necessary to somewhat increase the size of 30 so as to pass as much fuel as both 30 and 28 do in the described combination. In the combination system both 30 and 28 pass fuel for starting. Although the effective passage area of 28 is relatively small it contributes its share of starting fuel; and then serves alone for idling.

Fig. 3 shows a modification in which further modifications of functioning of the starting system are included, and in which an economizer function may also be incorporated.

In the forms `of either Fig. 1 or Fig. 2 the valve 38 or S0 may be so related to its seat and to the passage in which it stands open, that the pressure differential at which it will move off its seat and open is substantially less than the pressure differential that will initially move the valve to closed position. In fact, that is true of the valves of Figs. 1 and 2; the manifold depression must drop to a lesser amount than the starting depression in order to allow the valves to open. Such arrangements may be suffi-cient to keep the valves closed during all ordinary ranges of engine operation. But at exceptionally low speed at wide open throttle the differential between the manifold depression and the pressure in the fuel line 12 may not be sufficient to keep the valves on their seats against the spring or gravity tending to open them. In practice there must be some force such as the spring or gravity, which is sufficient to reliably and positively open' the valve when there is no manifold depression. And at low speed with wide open throttle the relative manifold depression may be so slight that the valve is apt to open if the valve opening force is large enough to be dependable. In the forms of Figs. l and 2 the pressure differential which may `open the valve is the differential between the manifold depression and the gas delivery pressure in 12.

'The form of Fig. 3 overcomes those diiculties mainly by utilizing a diaphragm of fairly large area acted on by the manifold depression. In that figure the passage 24, 26 restricted by calibrated orifice 30, leads from the intake manifold to a diaphragm chamber 100 under a diaphragm 102. Orifice 30 is large enough to pass the fuel required for starting. The other face of diaphragm 102 is exposed to the pressure in reference chamber 104, either atmospheric or, by balance tube 106, the pressure at the air entrance to the carbureter. A flat valve disk 108 on the lower face of the diaphragm is adapted to seat down on the valve seat formed by the upper end of a tube 110 whose large interior passage (larger than 30) is open at its lower end to the main gas passage 12. A spring 112 raises the valve disk 10S off its seat to open the passage through tube 110.

Assuming first that the passage tube 110 is fixed in position, the operation is as follows. One starting turnover the manifold depression is applied to diaphragm chamber 100 via orifice 30, that chamber being bled by the large passage in tube 110 connecting with the main gas passage 12. With valve 103 unseated, orifice 30 is of such size as to provide the desired over-rich mixture to the manifold with throttle in closed (idling) position. Spring 112 is of such strength as to hold valve 108 up in 'open position as long as the depression applied to orifice does not exceed that occurring during starting turn-over. With valve 10S open and the depression in 100 bled to passage 12, the depression in 100 is only a fraction of the manifold depression. Spring 112 consequently only has to hold diaphragm 102 up against a comparatively small effective depression applied to the diaphragm. But the effective area of the diaphragm being quite large, spring 112 can be amply strong to reliably open the valve 108 when there is no manifold depression. As soon as the engine starts, the increased depression in 100 due to increased depression applied to orifice 30 draws diaphragm 102 down to seat the valve 108 and thus close the bleed through tube 110. As soon as valve 108 closes, the diaphragm is then subjected to the full manifold depression which then keeps the valve closed during all ranges of engine operation. By making the diaphragm large enough the depression in at which a reliably strong spring 112 will open valve 108 can be made to be as small as desired; so that the valve will remain closed during the lowest manifold depressions occurring at the slowest speed with wide open throttle. For instance, the arrangement may be such that, wit-h a diaphragm of about 1%" effective diameter, spring 112 is strong enough to raise valve 10S at a manifold depression of, say, four inches of water in chamber 100. At any greater depression the valve will remain closed.

It will be noted that the eective depression which keeps the valve closed in this form of Fig. 3 is a depression measured against atmospheric pressure rather than against the delivery pressure in 12 as in Figs. 1 and 2. And another advantageous difference in Fig. 3 is due to the fact that the negative velocity head -of gas flow through 12 is also effective on the diaphragm to keep the valve 108 closed. At wide open throttle the gas velocity through 12 is high and the static pressure at tube 110 is correspondingly lowered. With the Valve 108 seated, that velocity depression is applied to the valve disk over the area of the tube. Thus the high velocity depression which occurs when the manifold depression is low, helps keep the valve closed.

If a fuel adjustment valve is used in the gas feed passage 12, as is usually the case where passage 12 is made of large enough size to suit different fuel gases, such adjustment valve is then arranged so that by adjustment it reduces the effective cross-section of passage 12 directly at the open end of tube 110. Such an arrangement is shown for the plug valve 120 which reduces the size of the passage by projecting adjustably into the passage 12. With such an arrangement the tube is located at the point of highest velocity in passage 12 and is therefore subject to the greatest possible pressure drop due to the gas feed velocity. And that pressure drop is particularly effective in holding valve 108 closed when the manifold depression is low at wide open throttle.

Of course, if the passage 12 is itself calibrated for the fuel gas that is being used, no adjustment valve such as is needed and every point in 12 is then a point of highest gas velocity.

Economized action may also be incorporated in the structure of Fig. 3. Tube 110 may be slidably mounted in the wall of passage 12, with suitable stops to limit its movement. For instance, a flange 122 on the lower end of the tube limits its upward movement, and the lower end of a sleeve 124, fixedly mounted on the tube, limits the downward movement by which the lower end of tube 110 can be projected into passage 12 to lreduce the effective cross-sectional area of that passage. Tube 110 has a sliding fit in the wall of passage 12, fitting closely enough that leakage through the fit is negligible. The upper end of sleeve 124 has a flange 126 and a spring 128 presses up on that flange to move and hold tube 110 up. Spring 128 is strong enough to hold the tube in its upper position unless the depression in chamber 100 is equal to about five inches of mercury.

The operation of the economizer, in combination with the starting system, is as follows. On turning over the engine to start, valve 108 stays in its upper open position as long as the manifold depression is that accompanying starting turn-over. (The same remarks and qualifications apply here as have been noted in connection with Figs. 1 and 2.) As soon as the engine starts and the depression in 100 increases above that of starting turnover, valve 108 seats on the upper end of tube 110, and chamber 100- is then subject to the full manifold depression. Spring 128 is chosen to. hold tube 1120 up against the downward diaphragm pressure due to, say, tive inches of mercury depression in 100, but to allow the tube to be moved down by the diaphragm at any greater depression; Consequently, during all` normal part load rangesY of operation where the manifold depression is more thanv that live inches, tube 110 will be projected into passage 12 to reduce the gas feed for economy of operation at part loads. The valve 108 follows the short movement of tube 110 and thus keeps the passage through that tube closed. As full load operation is approached, the manifold depression drops below the amount for which spring 128 is set, and the spring then pushes tube 110 and valve disk 108 and the diaphragm up; opening passage 12 for full gas flow. The valve 108 remains closed, as before explained, for depressions in 100 much lower than that at which spring 128 moves the valve assemblage up.

The depression measure given above as the one which controls economizer action happens to be the same as that previously named as a typical maximum starting depression for which the valve 108 will remain open. That relation is not at all necessary. The economizer controlling depression can be either greater or less than the starting depression. In any case the economizer controlling depression is less than the idling or middle range depression, so that the economizer action of lowering tube 110 takes place immediately that valve 108 closes as the engine goes into operation. Fuel for idling is of course supplied by means of passages independent of those shown here. An idling by-pass can of course be arranged between gas passage 12 and the intake manifold, in parallel relation to the starting passage formed by 110, 100, 30, 26 and 24; just as that idling by-pass parallels the starting passages in Figs. l and 2. And in that case the orifice 30 will be calibrated, as in those figures, to pass the required amount of starting fuel together with the idle by-pass.

The general operation of the form of Fig. 3 is the same as before given for the other figures. That is, the engine is first turned over a few turns with throttle closed down and then the throttle slowly opened as the turn over continues. The automatic throttle control shown in Fig. l may of course be used in connection with either Fig. 2 or Fig. 3.

The form of Fig. 3 may operate without an idling passage incorporated with it; or it may operate in conjunction with any suitable idling system, such for instance as the idling passages shown in Figs. I and 2. Thus, for instance, such an idle passage may be incorporated in the system of Fig. 3 by a passage 34a leading from 12 to the orifice 28a controlled by valve 32a. The action of this idling by-passwould be the same as in Figs. l and 2 and orifice 30 would be calibrated accordingly.

I claim:

l. In gaseous fuel feed systems for internal combustion engines and the like embodying a carbureter having an air intake, a mixture passage including a venturi throat formation, a throttle in the passage and the passage being adapted for connection to the engine intake beyond the throttle; the combination of a gas pressure regulator adapted to deliver fuel gas at a substantially constant pressure, a main fuel delivery passage leading from the regulator to the venturi throat, a diaphragm chamber and a diaphragm forming one of its walls, a starting fuel passage leading from the diaphragm chamber to the mixture passage beyond the throttle, a tubular member slidable through a wall of the main fue] passage with one open end in that passage and its opposite open end in the diaphrgam chamber in such relation to the diaphragm as to form a valve seat engageable by the diaphragm when the latter moves into its chamber, a spring tending Vto move the tubular member in a direction away from the main fuel passage and toward to the diaphragm, means limiting that movement, and another lighter spring tending to move the diaphragm outwardly of its chamber and away from the tubular member, said tubular member being projectible into the main fuel passage by diaphragm movement into its diaphragm chamber.

2. The combination defined in claim 1 and including also means for adjustably restricting the cross-sectional area of the main fuel delivery passage at the point where said tube projects into it.

3. InY gaseous fuel feed systems for internal combustion engines and the like embodying a carbureter having an air intake, a mixture passage including a venturi throat formation, a throttle in the passage and the passage being adapted for connection to the engine intake beyond the throttle; the combination of a gas pressure regulator adapted to deliver fuel gas a substantially constant pressure, a main fuel delivery passage leading from the regulator to the venturi throat, a diaphragm chamber and a diaphragm forming one of its walls, a starting fuel passage leading from the diaphragm chamber to the mixture passage beyond the throttle, a passage leading from the main fuel delivery passage at a point close to the venturi into the diaphragm chamber and terminating in a valve seat, both the starting fuel passage and the last mentioned passage being of a size sutiicient to pass the fuel required for starting, a valvular member connected to the diaphragm and adapted to be seated on said valve seat by virtue of movement of the diaphragm inwardly into its chamber, means exerting a constant force on the diaphragm and valve member tending to keep the member unseated, said valve seat passage being formed by a tube which has one end projecting into the main fuel delivery passage and is limitedly slidable to project into that passage by a variable amount, and means exerting a constant force tending to move the tube in a direction outward of the fuel delivery passage.

4. The combination defined in claim 3 and including also means for adjustably restricting the cross-sectional area of the fuel delivery passage at the point where said tuberprojects into it.

5. In gaseous fuel feed systems for internal combustion engines and the like embodying a carbureter having an air intake, a mixture passage including a venturi throat formation, a throttle in the passage and the passage being adapted for connection to the engine intake beyond the throttle; the combination of a gas pressure regulator adapted to deliver fuel gas at a substantially constant pressure, a main fuel delivery passage leading from the regulator to the venturi throat, a starting fuel passage means leading from the main fuel passage, at a position between the regulator and the venturi throat and close to the venturi throat, to the mixture passage at a point beyond the throttle, said starting fuel passage means being of a total elfective size throughout its length suliicient to pass the gaseous fuel required for starting on starting turn-over of the engine, normally open valve means controlling said starting fuel passage means, and depression actuated means in association with the valve means and acting to cause the valve means to move to prevent tiow through at least a portion of said starting fuel passage means by virtue of the existence in the engine intake of a depression greater than the accompanying normal turnover of the engine for starting with the throttle in substantially its closed position for idling.

6. The combination defined in claim 5, in which the starting fuel passage means is composed of two passages in parallel, one of said passages being of an eifective size to provide the gaseous fuel required for idling, the other of said passages being controlled by said valve means, and said depression actuated means acting to cause the valve means to move to completely close said other passage by virtue of the existence in the engine intake of a depression greater than that accompanying normal turnover of the engine for starting with the throttle in substantially its closed position for idling.

7. The combination defined in claim 6 and including means, actuated by virtue of existence of starting turnover depression in the intake, to slowly open the throttle.

8. The combination defined in claim 5 and including means, actuated by virtue of existence of starting turnover depression in the intake, to slowly open the throttle.

9. The combination defined in claim 5 and including also means, in association with the valve means and the depression actuated means, acting to hold the valve means closed down, after initial closure, by virtue of a lesser manifold depression than that required to close it down from open position.

10. The combination defined in claim 5, in which the starting fuel passage means is composed of two passages in parallel, one of said passages being of an eifective size to provide the gaseous fuel required for idling, the other of said passages being controlled by said valve means, and said depression actuated means acting to cause the valve means to move to completely close said other passage by virtue of the existence in the engine intake of a depression greater than that accompanying normal turnover of the engine for starting with the throttle in substantially its closed position for idling, and means, in association with the valve means and the depression actuated means, acting to hold the valve means closed, after initial closure, by virtue of a lesser manifold depression than that required to iclose it from open position.

11. In gaseous fuel feed systems for internal combustion engines and the like embodying a carbureter having an air intake, a mixture passage including a venturi throat formation, a throttle in the passage and the passage being adapted for connection to the engine intake beyond the throttle; the combination of a gas pressure regulator adapted to deliver fuel gas at a substantially constant pressure, a main fuel delivery passage leading from the regulator to the venturi throat, a diaphragm chamber and a diaphragm forming one of its walls, a constantly open starting fuel passage leading from the diaphragm chamber to the mixture passage beyond the throttle, a passage leading from the main fuel delivery passage from a point close to the venturi throat into the diaphragm chamber and terminating in a valve seat, both the starting fuel passage and the last mentioned passage being throughout of a size suicient to pass the gaseous fuel required for starting on starting turn-over of the engine, a valvular member connected to the diaphragm and adapted to be seated on said valve seat by virtue of movement of the diaphragm inwardly into its chamber, and means exerting a constant force on the diaphragm and valvular member tending to keep that member unseated.

12. The combination defined in claim l1 and in which the valvular member is so related to the valve seat, and the passage which leads to the valve seat is so related to the fuel delivery passage at its end communicating with that passage, that depression due to the velocity of fuel ow through the fuel delivery passage tends to keep the valve member seated, and means for adjustably restricting the effective cross-sectional area of the fuel delivery passage at the point of communication of the valve seat passage therewith.

References cited in the me of this patent UNITED STATES PATENTS 2,073,299 Ensign Mar. 9, 1937 2,314,580 Garretson Mar. 23, 1943 2,414,322 Mock Jan. 14, 1947 2,568,987 Brunner Sept. 25, 1951 2,595,721 Snyder May 6, 1952 2,597,335 Jones May 20, 1952 

2. IN GASEOUS FUEL FEED SYSTEMS FOR INTERNAL COMBUSTION ENGINES AND THE LIKE EMBODYING A CARBURETER HAVING AN AIR INTAKE, A MIXTURE PASSAGE INCLUDING A VENTURI THROAT FORMATION, A THROTTLE IN THE PASSAGE AND THE PASSAGE BEING ADAPTED FOR CONNECTION TO THE ENGINE INTAKE BEYOND THE THROTTLE; THE COMBINATION OF A GAS PRESURE REGULATOR ADAPTED TO DELIVER FUEL GAS AT A SUBSTANTIALLY CONSTANT PRESSURE, A MAIN FUEL DELIVERY PASSAGE LEADING FROM THE REGULATOR TO THE VENTURI THROAT, A STARTING FUEL PASSAGE MEANS LEADING FROM THE MAIN FUEL PASSAGE, AT A POSITION BETWEEN THE REGULATOR AND THE VENTURI THROAT AND CLOSE TO THE VENTURI THROAT, TO THE MIXTURE PASSAGE AT A POINT BEYOND THE THROTTLE, SAID STARTING FUEL PASSAGE MEANS BEING OF A TOTAL EFFECTIVE SIZE THROUGHOUT ITS LENGTH SUFFICIENT TO PASS THE GASEOUS FUEL REQUIRED FOR STARTING ON STARTING TURN-OVER OF THE ENGINE, NORMALLY OPEN VALVE MEANS CONTROLLING SAID STARTING FUEL PASSAGE MEANS, AND DEPRESSION ACTUATED MEANS IN ASSOCIATION WITH THE VALVE MEANS AND ACTING TO CAUSE THE VALVE MEANS TO MOVE TO PREVENT FLOW THROUGH AT LEAST A PORTION OF SAID STARTING FUEL PASSAGE MEANS BY VIRTUE OF THE EXISTENCE IN THE ENGINE INTAKE OF A DEPRESSION GREATER THAN THE ACCOMPANYING NORMAL TURNOVER OF THE ENGINE FOR STARTING WITH THE THROTTLE IN SUBSTANTIALLY ITS CLOSED POSITION FOR IDILING. 